server-info.c

   1 #include "git-compat-util.h"
   2 #include "alloc.h"
   3 #include "dir.h"
   4 #include "environment.h"
   5 #include "hex.h"
   6 #include "repository.h"
   7 #include "refs.h"
   8 #include "object.h"
   9 #include "commit.h"
  10 #include "tag.h"
  11 #include "packfile.h"
  12 #include "path.h"
  13 #include "object-file.h"
  14 #include "object-store-ll.h"
  15 #include "server-info.h"
  16 #include "strbuf.h"
  17 #include "wrapper.h"
  18
  19 struct update_info_ctx {
  20         FILE *cur_fp;
  21         FILE *old_fp; /* becomes NULL if it differs from cur_fp */
  22         struct strbuf cur_sb;
  23         struct strbuf old_sb;
  24 };
  25
  26 static void uic_mark_stale(struct update_info_ctx *uic)
  27 {
  28         fclose(uic->old_fp);
  29         uic->old_fp = NULL;
  30 }
  31
  32 static int uic_is_stale(const struct update_info_ctx *uic)
  33 {
  34         return uic->old_fp == NULL;
  35 }
  36
  37 __attribute__((format (printf, 2, 3)))
  38 static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
  39 {
  40         va_list ap;
  41         int ret = -1;
  42
  43         va_start(ap, fmt);
  44
  45         if (uic_is_stale(uic)) {
  46                 ret = vfprintf(uic->cur_fp, fmt, ap);
  47         } else {
  48                 ssize_t r;
  49                 struct strbuf *cur = &uic->cur_sb;
  50                 struct strbuf *old = &uic->old_sb;
  51
  52                 strbuf_reset(cur);
  53                 strbuf_vinsertf(cur, 0, fmt, ap);
  54
  55                 strbuf_reset(old);
  56                 strbuf_grow(old, cur->len);
  57                 r = fread(old->buf, 1, cur->len, uic->old_fp);
  58                 if (r != cur->len || memcmp(old->buf, cur->buf, r))
  59                         uic_mark_stale(uic);
  60
  61                 if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
  62                         ret = 0;
  63         }
  64
  65         va_end(ap);
  66
  67         return ret;
  68 }
  69
  70 /*
  71  * Create the file "path" by writing to a temporary file and renaming
  72  * it into place. The contents of the file come from "generate", which
  73  * should return non-zero if it encounters an error.
  74  */
  75 static int update_info_file(char *path,
  76                         int (*generate)(struct update_info_ctx *),
  77                         int force)
  78 {
  79         char *tmp = mkpathdup("%s_XXXXXX", path);
  80         int ret = -1;
  81         int fd = -1;
  82         FILE *to_close;
  83         struct update_info_ctx uic = {
  84                 .cur_fp = NULL,
  85                 .old_fp = NULL,
  86                 .cur_sb = STRBUF_INIT,
  87                 .old_sb = STRBUF_INIT
  88         };
  89
  90         safe_create_leading_directories(path);
  91         fd = git_mkstemp_mode(tmp, 0666);
  92         if (fd < 0)
  93                 goto out;
  94         to_close = uic.cur_fp = fdopen(fd, "w");
  95         if (!uic.cur_fp)
  96                 goto out;
  97         fd = -1;
  98
  99         /* no problem on ENOENT and old_fp == NULL, it's stale, now */
 100         if (!force)
 101                 uic.old_fp = fopen_or_warn(path, "r");
 102
 103         /*
 104          * uic_printf will compare incremental comparison against old_fp
 105          * and mark uic as stale if needed
 106          */
 107         ret = generate(&uic);
 108         if (ret)
 109                 goto out;
 110
 111         /* new file may be shorter than the old one, check here */
 112         if (!uic_is_stale(&uic)) {
 113                 struct stat st;
 114                 long new_len = ftell(uic.cur_fp);
 115                 int old_fd = fileno(uic.old_fp);
 116
 117                 if (new_len < 0) {
 118                         ret = -1;
 119                         goto out;
 120                 }
 121                 if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
 122                         uic_mark_stale(&uic);
 123         }
 124
 125         uic.cur_fp = NULL;
 126         if (fclose(to_close))
 127                 goto out;
 128
 129         if (uic_is_stale(&uic)) {
 130                 if (adjust_shared_perm(tmp) < 0)
 131                         goto out;
 132                 if (rename(tmp, path) < 0)
 133                         goto out;
 134         } else {
 135                 unlink(tmp);
 136         }
 137         ret = 0;
 138
 139 out:
 140         if (ret) {
 141                 error_errno("unable to update %s", path);
 142                 if (uic.cur_fp)
 143                         fclose(uic.cur_fp);
 144                 else if (fd >= 0)
 145                         close(fd);
 146                 unlink(tmp);
 147         }
 148         free(tmp);
 149         if (uic.old_fp)
 150                 fclose(uic.old_fp);
 151         strbuf_release(&uic.old_sb);
 152         strbuf_release(&uic.cur_sb);
 153         return ret;
 154 }
 155
 156 static int add_info_ref(const char *path, const struct object_id *oid,
 157                         int flag UNUSED,
 158                         void *cb_data)
 159 {
 160         struct update_info_ctx *uic = cb_data;
 161         struct object *o = parse_object(the_repository, oid);
 162         if (!o)
 163                 return -1;
 164
 165         if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
 166                 return -1;
 167
 168         if (o->type == OBJ_TAG) {
 169                 o = deref_tag(the_repository, o, path, 0);
 170                 if (o)
 171                         if (uic_printf(uic, "%s %s^{}\n",
 172                                 oid_to_hex(&o->oid), path) < 0)
 173                                 return -1;
 174         }
 175         return 0;
 176 }
 177
 178 static int generate_info_refs(struct update_info_ctx *uic)
 179 {
 180         return for_each_ref(add_info_ref, uic);
 181 }
 182
 183 static int update_info_refs(int force)
 184 {
 185         char *path = git_pathdup("info/refs");
 186         int ret = update_info_file(path, generate_info_refs, force);
 187         free(path);
 188         return ret;
 189 }
 190
 191 /* packs */
 192 static struct pack_info {
 193         struct packed_git *p;
 194         int old_num;
 195         int new_num;
 196 } **info;
 197 static int num_pack;
 198
 199 static struct pack_info *find_pack_by_name(const char *name)
 200 {
 201         int i;
 202         for (i = 0; i < num_pack; i++) {
 203                 struct packed_git *p = info[i]->p;
 204                 if (!strcmp(pack_basename(p), name))
 205                         return info[i];
 206         }
 207         return NULL;
 208 }
 209
 210 /* Returns non-zero when we detect that the info in the
 211  * old file is useless.
 212  */
 213 static int parse_pack_def(const char *packname, int old_cnt)
 214 {
 215         struct pack_info *i = find_pack_by_name(packname);
 216         if (i) {
 217                 i->old_num = old_cnt;
 218                 return 0;
 219         }
 220         else {
 221                 /* The file describes a pack that is no longer here */
 222                 return 1;
 223         }
 224 }
 225
 226 /* Returns non-zero when we detect that the info in the
 227  * old file is useless.
 228  */
 229 static int read_pack_info_file(const char *infofile)
 230 {
 231         FILE *fp;
 232         struct strbuf line = STRBUF_INIT;
 233         int old_cnt = 0;
 234         int stale = 1;
 235
 236         fp = fopen_or_warn(infofile, "r");
 237         if (!fp)
 238                 return 1; /* nonexistent is not an error. */
 239
 240         while (strbuf_getline(&line, fp) != EOF) {
 241                 const char *arg;
 242
 243                 if (!line.len)
 244                         continue;
 245
 246                 if (skip_prefix(line.buf, "P ", &arg)) {
 247                         /* P name */
 248                         if (parse_pack_def(arg, old_cnt++))
 249                                 goto out_stale;
 250                 } else if (line.buf[0] == 'D') {
 251                         /* we used to emit D but that was misguided. */
 252                         goto out_stale;
 253                 } else if (line.buf[0] == 'T') {
 254                         /* we used to emit T but nobody uses it. */
 255                         goto out_stale;
 256                 } else {
 257                         error("unrecognized: %s", line.buf);
 258                 }
 259         }
 260         stale = 0;
 261
 262  out_stale:
 263         strbuf_release(&line);
 264         fclose(fp);
 265         return stale;
 266 }
 267
 268 static int compare_info(const void *a_, const void *b_)
 269 {
 270         struct pack_info *const *a = a_;
 271         struct pack_info *const *b = b_;
 272
 273         if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
 274                 /* Keep the order in the original */
 275                 return (*a)->old_num - (*b)->old_num;
 276         else if (0 <= (*a)->old_num)
 277                 /* Only A existed in the original so B is obviously newer */
 278                 return -1;
 279         else if (0 <= (*b)->old_num)
 280                 /* The other way around. */
 281                 return 1;
 282
 283         /* then it does not matter but at least keep the comparison stable */
 284         if ((*a)->p == (*b)->p)
 285                 return 0;
 286         else if ((*a)->p < (*b)->p)
 287                 return -1;
 288         else
 289                 return 1;
 290 }
 291
 292 static void init_pack_info(const char *infofile, int force)
 293 {
 294         struct packed_git *p;
 295         int stale;
 296         int i;
 297         size_t alloc = 0;
 298
 299         for (p = get_all_packs(the_repository); p; p = p->next) {
 300                 /* we ignore things on alternate path since they are
 301                  * not available to the pullers in general.
 302                  */
 303                 if (!p->pack_local || !file_exists(p->pack_name))
 304                         continue;
 305
 306                 i = num_pack++;
 307                 ALLOC_GROW(info, num_pack, alloc);
 308                 CALLOC_ARRAY(info[i], 1);
 309                 info[i]->p = p;
 310                 info[i]->old_num = -1;
 311         }
 312
 313         if (infofile && !force)
 314                 stale = read_pack_info_file(infofile);
 315         else
 316                 stale = 1;
 317
 318         for (i = 0; i < num_pack; i++)
 319                 if (stale)
 320                         info[i]->old_num = -1;
 321
 322         /* renumber them */
 323         QSORT(info, num_pack, compare_info);
 324         for (i = 0; i < num_pack; i++)
 325                 info[i]->new_num = i;
 326 }
 327
 328 static void free_pack_info(void)
 329 {
 330         int i;
 331         for (i = 0; i < num_pack; i++)
 332                 free(info[i]);
 333         free(info);
 334 }
 335
 336 static int write_pack_info_file(struct update_info_ctx *uic)
 337 {
 338         int i;
 339         for (i = 0; i < num_pack; i++) {
 340                 if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
 341                         return -1;
 342         }
 343         if (uic_printf(uic, "\n") < 0)
 344                 return -1;
 345         return 0;
 346 }
 347
 348 static int update_info_packs(int force)
 349 {
 350         char *infofile = mkpathdup("%s/info/packs", get_object_directory());
 351         int ret;
 352
 353         init_pack_info(infofile, force);
 354         ret = update_info_file(infofile, write_pack_info_file, force);
 355         free_pack_info();
 356         free(infofile);
 357         return ret;
 358 }
 359
 360 /* public */
 361 int update_server_info(int force)
 362 {
 363         /* We would add more dumb-server support files later,
 364          * including index of available pack files and their
 365          * intended audiences.
 366          */
 367         int errs = 0;
 368
 369         errs = errs | update_info_refs(force);
 370         errs = errs | update_info_packs(force);
 371
 372         /* remove leftover rev-cache file if there is any */
 373         unlink_or_warn(git_path("info/rev-cache"));
 374
 375         return errs;
 376 }